Spinal correction and secondary stabilization

ABSTRACT

Methods of correcting a spinal deformity include securing a first rod on a first side of a spine, securing an anchor on a second side of a spine, securing a lateral coupling between the rod and the anchor, translating and derotating the spine to correct the spinal deformity by adjusting an effective length of the lateral coupling, and securing a second rod on a second side of the spine to provide secondary stabilization to the spine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. 120 to, and is acontinuation-in-part of U.S. application Ser. No. 13/297,841, filed Nov.16, 2011, and titled, “Spinal Correction and Secondary Stabilization,”the entire contents of which are incorporated herein by reference.

INCORPORATION BY REFERENCE OF ADDITIONAL DISCLOSURES

Additional examples of system components and corrective methodology inaccordance with various embodiments of the present invention are setforth in U.S. App. Pub. 2010/0318129, filed Jun. 16, 2009 and entitled“Deformity Alignment System with Reactive Force Balancing”; U.S. App.Pub. 2010/0249837, filed Mar. 26, 2009 and entitled “Semi-ConstrainedAnchoring System”; U.S. App. Pub. 2011/0054536, filed Sep. 1, 2010 andentitled “Growth Directed Vertebral Fixation System with DistractibleConnector(s) and Apical Control”; U.S. Pat. No. 7,658,753, issued Feb.9, 2010 and entitled “Device and Method for Correcting a SpinalDeformity”; and U.S. App. Pub. 2009/0012565, filed on Jun. 5, 2008 andentitled “Medical Device and Method to Correct Deformity,” the entirecontents of each of which are hereby incorporated by reference for allpurposes.

BACKGROUND

Many systems have been utilized to treat spinal deformities such asscoliosis, spondylolisthesis, and a variety of others. Primary surgicalmethods for correcting a spinal deformity utilize instrumentation tocorrect the deformity as much as possible and separate implantablehardware systems to rigidly stabilize and maintain the correction.

SUMMARY

Some aspects relate to methods of correcting a spinal deformity,including securing a first rod on a first side of a spine, securing ananchor on a second side of the spine, securing a lateral couplingbetween the rod and the anchor, translating and derotating the spine tocorrect the spinal deformity by adjusting an effective length of thelateral coupling, and securing a second rod on the second side of thespine to provide secondary stabilization to the spine.

Some aspects relate to a system for correcting a spinal deformity, thesystem including first and second rods; first, second, third, and fourthanchors; and a lateral coupling. The first and second rods are adaptedto extend along first and second sides, respectively, of a spine of apatient. The first anchor is adapted to be fixed to a vertebra of thespine and to receive the first rod such that the first rod is securedagainst substantial lateral translation relative to the first anchor andthe first rod is allowed to slide axially relative to the first anchorthrough a first pivot point and to change in at least two of pitch, yaw,and roll about the first pivot point. The second anchor is also adaptedto be fixed to a vertebra of the spine and to receive the first rod suchthat the first rod is secured against substantial lateral translationrelative to the second stabilizing anchor and is allowed to change in atleast pitch and yaw about a second pivot point. The third anchor isadapted to be fixed to a vertebra of the spine and to receive the secondrod such that the second rod is secured against substantial lateraltranslation relative to the third anchor. The fourth anchor is adaptedto be fixed to a vertebra of the spine and to receive the second rodsuch that the second rod is secured against substantial lateraltranslation relative to the fourth anchor. The lateral coupling isadapted to extend between and laterally secure the first rod and thesecond rod.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an implantable spinal correction andfusion system, according to some embodiments.

FIG. 2 is a cross-sectional view of a spinal rod of the system of FIG.1, according to some embodiments.

FIG. 3 is a cross-sectional view of a stabilizing anchor of the systemof FIG. 1, according to some embodiments.

FIG. 4 is an isometric view of the stabilizing anchor of FIG. 3 with aninsertion sleeve in a retention orientation, according to someembodiments.

FIG. 5 is a plan view of the stabilizing anchor of FIG. 3 with theinsertion sleeve in the retention orientation, according to someembodiments.

FIG. 6 is an isometric view of the stabilizing anchor of FIG. 3 with theinsertion sleeve in an insertion orientation, according to someembodiments.

FIG. 7 is a plan view of the stabilizing anchor of FIG. 3, with theinsertion sleeve in the insertion orientation, according to someembodiments.

FIG. 8 is a front view of the stabilizing anchor of FIG. 3, with theinsertion sleeve in the insertion orientation, according to someembodiments.

FIG. 9 is an isometric view of another stabilizing anchor of the systemof FIG. 1, according to some embodiments.

FIG. 10 is an isometric view of an anchor of the system of FIG. 1,according to some embodiments.

FIG. 11 is an isometric view of a transverse anchor of the system ofFIG. 1, according to some embodiments.

FIG. 12 is an isometric view of an actuation assembly of the system ofFIG. 1, according to some embodiments.

FIG. 13 is a cross-section view of a portion of the actuation assemblyof FIG. 12, according to some embodiments.

FIG. 14 is a bottom view of the actuation assembly of FIG. 12 with aportion of a clamshell housing removed, according to some embodiments.

FIG. 15 is a bottom view of the actuation assembly of FIG. 12, accordingto some embodiments.

FIG. 16 is a cross-sectional view of a connector head and tether of theactuation assembly of FIG. 12, according to some embodiments.

FIG. 17 is a cross-sectional view of the actuation assembly of FIG. 12,showing the connector head and tether in an extended state and aretracted state, according to some embodiments.

FIG. 18 is an isometric view of the system of FIG. 1 during a correctionprocedure, according to some embodiments.

FIGS. 19 and 20 are isometric views of the system of FIG. 1 before andafter assembly of a second rod into the system, according to someembodiments.

FIGS. 21 to 23 are isometric views of the system of FIG. 1 showing aprocess of separating and removing portions of the first rod andstabilizing anchors, according to some embodiments.

FIG. 24 is an isometric view of a system of another configuration,according to some embodiments.

FIG. 25 is an isometric view of another anchor of an implantable spinalcorrection and fusion system, according to some embodiments.

FIG. 26 is an isometric view of another anchor of an implantable spinalcorrection and fusion system, according to some embodiments.

FIG. 27 shows another configuration for an implantable spinal correctionand fusion system, according to some embodiments.

FIG. 28 shows another configuration for an implantable spinal correctionand fusion system, according to some embodiments.

FIG. 29 shows another configuration for an implantable spinal correctionand fusion system, according to some embodiments.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

Some embodiments relate to a spinal correction and fusion system forimplantation into a patient, as well as associated methods and devices.In general terms, the system provides for lateral translationalcorrective force(s) and/or derotational corrective force(s) on a spinalcolumn with associated instrumentation for facilitating vertebral fusionat a selected region of the spine. Some features of the system includeimplementation of a first, relatively longer rod for initial correction,a second, shorter rod for secondary spinal stabilization. If desired,the secondary stabilization helps promote a fusion process. In someembodiments, the spine retains freedom of motion above and below thespinal segment corresponding to the shorter rod, with the first,relatively longer rod remaining implanted. In other embodiments, thefirst, relatively longer rod is trimmed and removed following correctionof the spinal column and implementation of the second, shorter rod. Avariety of additional features and advantages of the inventive systemsare contemplated and provided by the instant disclosure.

FIG. 1 shows a spinal correction and fusion system 10, the system 10including a first rod 12; a second rod 14; a plurality of anchors,including a first stabilizing anchor 16, a second stabilizing anchor 18,a first anchor 20, a second anchor 22, a third anchor 24, a fourthanchor 26; a first transverse anchor 28; a second transverse anchor 30;a first adjustment assembly 32; a second adjustment assembly 34; and aplurality of fasteners 36, such as bone screws, for securing componentsof the system 10 to a spine, or spinal column 40 having a first side 40Aand a second side 40B. The system 10 is optionally used to bring thespine 40 to a more natural curvature (e.g., using a single adjustment).In other embodiments, an abnormal curvature in the spinal column 40 hasbeen adjusted to a more natural curvature using other hardware, prior toor in conjunction with securing portions of the system 10 to the spinalcolumn 40. In some embodiments, the system 10 is adapted to initiallyprovide means for leveraged correction, with translation and derotationof the spine. If desired, the system 10 is adapted to provide means forselective fusion of the spine following correction. In otherembodiments, the system 10 provides means for maintaining a correctionto facilitate spine remodeling without vertebral fusion, or withoutpermanent vertebral fusion.

Although the system 10 is shown with a select number of components, suchas two stabilizing anchors 16, 18 two transverse anchors 28, 30, and twoadjustment assemblies 32, 34, more or fewer are implemented asappropriate. For example, in some embodiments a single transverseanchor, such as the first transverse anchor 28, is secured to one ormore of a plurality of vertebrae 42 at an apex A of a spinaldeformation, with a corresponding adjustment assembly, such as the firstadjustment assembly 32, coupled to the transverse anchor 28. Moreover,although four anchors 20, 22, 24, 26 are shown, in some embodimentsthere are more or less of the anchors. For example, in some embodimentsthe system 10 includes the first rod 12, the second rod 14, a singletransverse anchor, such as the transverse anchor 28 and a single anchor,such as the third anchor 24, with the second rod 14 secured between thetransverse anchor 28 and the third anchor 24. In still otherembodiments, the system 10 does not include any of the anchors 20, 22,24, 26, but instead the second rod 14 is secured between the first andsecond transverse anchors 28, 30 (see, e.g., FIG. 24). A variety ofother configurations are also contemplated.

Various planes and associated directions are referenced in the followingdescription, including a sagittal plane defined by two axes, one drawnbetween a head (superior) and tail (inferior) of the body and one drawnbetween a back (posterior) and front (anterior) of the body; a coronalplane defined by two axes, one drawn between a center (medial) to side(lateral) of the body and one drawn between a head (superior) and tail(inferior) of the body; and a transverse plane defined by two axes, onedrawn between a back and front of the body and one drawing between acenter and side of the body. The terms pitch, roll, and yaw are alsoused, where roll generally refers to angulation, or rotation, in a firstplane through which a longitudinal axis of a body orthogonally passes(e.g., rotation about a longitudinal axis corresponding to the spinalcolumn), pitch refers to angulation, or rotation, in a second planeorthogonal to the first plane, and yaw refers to angulation, orrotation, in a third plane orthogonal to the first and second planes. Insome embodiments, pitch is angulation in the sagittal plane, yaw isangulation in the coronal plane, and roll is angulation in thetransverse plane.

In various embodiments, changes in pitch, yaw, and/or roll occurconcurrently or separately as desired. Moreover, as used herein,“lateral translation” is not limited to translation in themedial-lateral direction unless specified as such.

As shown in FIG. 1, in some embodiments the first rod 12, also describedas an elongate member, is secured to the spinal column 40 at apre-selected offset from a longitudinal axis of the spinal column 40.For example, the first rod 12 is optionally secured at an offset along amedial-lateral axis ML, or right-left axis, and anterior-posterior axisAP, or back-front axis. In some embodiments, the first rod 12 is securedon the left side of the spinal column 40 as shown. As subsequentlydescribed, the offset is optionally selected to cause at least arelative lateral translation (e.g., central or medial movement) andderotational shift of selected vertebrae 42 of the spinal column 40(relative anterior-posterior movement of selected vertebrae 42 can alsobe accomplished) such that the spinal column 40 exhibits a more naturalposition.

The first rod 12 is elongate and cylindrical including a superiorportion 50, an intermediate portion 52, and an inferior portion 54. Thefirst rod 12 is adapted, or otherwise structured, to extend along thespinal column 40. The first rod 12 is optionally contoured to complementa desired spinal curvature (e.g., generally following the curvature of acorrected, or natural spine as shown in FIG. 20). In some embodiments,the first rod 12 is substantially rigid, defining a substantially roundcross-section with a mean diameter of about 6 mm and being formed of asuitable biocompatible material, such as titanium alloy ASTM F136, orcobalt chromium alloy ASTM F1537 or any other suitable implantablematerial. If desired, the first rod 12 incorporates some flex, orspringiness while substantially rigidly retaining its shape. The firstrod 12 is optionally formed of a variety of materials, includingstainless steel or suitable polymeric materials.

The first rod 12 has a longitudinal axis X—where the rod 12 issubstantially straight, the longitudinal axis X is substantiallystraight and, where the rod 12 is substantially curved or angled, thelongitudinal axis X is similarly curved or angled. The sections 50, 52,54 of the first rod 12 are optionally continuously formed or are formedas separate, connected parts as desired. In still other embodiments,expandable rod designs are also contemplated.

FIG. 2 is a cross-sectional view of the first rod 12 in the inferiorportion 54 of the first rod 12. As shown, the cross-sectional shape ofthe first rod 12, including various portions thereof, is not limited tocircular cross-sections. For example, the inferior portion 54 optionallyincludes a plurality of splines 60 for mating with the first stabilizinganchor 16. As shown in FIG. 2, the splines 60 are trapezoidal (e.g.,similarly to the teeth of a gear) with rounded bases, although a varietyof shapes, such as involute shapes, are contemplated.

As shown in FIG. 1, the second rod 14 is substantially shorter than thefirst rod 12. For example, the second rod 14 is optionally configured(e.g., having a corresponding length and/or longitudinal contour) toextend along an apical region A of the spine 40 and/or between a desirednumber of anchors, such as the third and fourth anchors 24, 26. Thesecond rod 14 is optionally formed of similar materials and with similarcross-section(s) to that of the first rod 12, as desired.

FIGS. 3 to 8 show the first stabilizing anchor 16 (also described as arod anchor) of the system 10, according to some embodiments. As shown inFIG. 1, the first stabilizing anchor 16 is adapted, or otherwisestructured, to be mounted, or fixed to one or more of the vertebrae 42,such as a first vertebra 42A (FIG. 1) located at an inferior position,or other position, along the spine 40.

As shown in FIG. 3, the first stabilizing anchor 16 is adapted toreceive, and includes means for receiving, the first rod 12 such thatthe first rod 12 is secured laterally, against lateral translationrelative to the first stabilizing anchor 16. In some embodiments, thefirst rod 12 is substantially prevented from translating in a directionsubstantially perpendicular to the longitudinal axis X at a first pivotpoint P1. In turn, the first rod 12 is able to slide axially, ortranslate axially, along the longitudinal axis X of the first rod 12,relative to the first stabilizing anchor 16 through the first pivotpoint P1. The rod 12 is also able to change in pitch and yaw about thefirst pivot point P1. The first stabilizing anchor 16 is adapted, orotherwise structured, to limit rotation, or roll, of the first rod 12about the longitudinal axis X of the first rod 12. In particular, thefirst stabilizing anchor 16 provides means for allowing the rod 12 toangulate without substantial lateral translation relative to the firststabilizing anchor 16 and without substantial rotation about thelongitudinal axis X.

FIG. 4 is an isometric view of the first stabilizing anchor 16. Asshown, the first stabilizing anchor 16 is optionally formed ofbiocompatible materials and includes a mounting portion 70 and a housingportion 72. The mounting portion 70 is adapted to secure the firststabilizing anchor 16 to one or more vertebrae 42, such as the firstvertebra 42A and an additional vertebra 42 above or below the firstvertebra 42A. In other embodiments, the mounting portion 70 is securedto a single vertebra, such as the first vertebra 42A (e.g., laterallyacross the first vertebra 70B at the pedicles, or at a single point—suchas a single pedicle—on the first vertebra 26A. In some embodiments, themounting portion 70, also described as a plate, is adapted to be securedat two or more points, for example spanning between two vertebrae 42(e.g., the L3-L4 vertebrae) or spanning across a portion of a singlevertebra 42 (e.g., pedicle-to-pedicle on a single vertebra).

In some embodiments, the mounting portion 70 includes a pedestal withfirst and second anchor locations, each of the anchor locations defininga surface suitable for mounting the first stabilizing anchor 16 to oneor more vertebrae 42. The first and second anchor locations eachoptionally include through holes 74 for receiving one of the fasteners36, such as a pedicle screw or similar device to secure the mountingportion 70 to one or more vertebrae 42, such as the first vertebra 42A.

The housing portion 72 of the first stabilizing anchor 16 includes abody 80 and a sleeve insert 82. In some embodiments, the sleeve insert82 is substantially spherical in shape and the body 80 forms asubstantially spherical mating race for receiving the sleeve insert 82.The body 80 has a sleeve aperture 84 (FIG. 5) extending front-to-backthrough the body 80, the sleeve aperture 84 defining a revolute,substantially concave articulation surface 86 (FIG. 5). The sleeveinsert 82, in turn, forms a complementary revolute, substantially convexarticulation surface 88. As shown in FIG. 3, the body 80 also has a pinchase 90 (e.g., a cylindrical through hole) that defines a terminal seat92 having a larger diameter than a remainder of the pin chase 90.

FIG. 5 is a plan view of the first stabilizing anchor 16, showing thesleeve insert 82 as it would be received within the body 80 (thoughnormally hidden from view). As shown, the concave articulation surface86 of the aperture 84 defines opposed apices 89 on each side of thearticulation surface 86. The articulation surfaces 86, 88 are adapted,or otherwise structured, to form a substantially complementary fit withone another, such that the sleeve insert 82 is able to be captured bythe body 80 within the aperture 94 and have relative angular movementwith respect to the body 80. To facilitate assembly of the sleeve insert82 into the body 80, the aperture 84 includes first and second channels94, 96 formed into the articulation surface 86 at the apices 89 suchthat the minimum effective internal diameter D of the aperture 84 isincreased between the channels 94, 96. The channels 94, 96 extend frontto back through the body 80 and are positioned on opposite sides of thebody 80. While two channels are shown, in other embodiments a singlechannel is included. FIG. 8 is a front view of the stabilizing anchor16. As shown in FIGS. 5 and 8, the channels 94, 96 have arcuate profilesand extend into the aperture 84 to the apices 89 on each side of thearticulation surface 86. The profiles of the channels 94, 96 areoptionally complementary in shape to a portion of the profile—thelateral edges, or sides—of the sleeve insert 82 such that the sleeveinsert 82 is able to be received through the channels 94, 96 into theaperture 84 when the sleeve insert 82 is oriented perpendicular, oredgewise relative to the body 80. The body 80 also includes a protrusion98 (FIG. 3) (e.g., a pin) or protrusions (not shown) that extendsinwardly into the aperture 84 from the articulation surface 86.

As shown in FIG. 3, the sleeve insert 82 has a passage 100 defining thepivot point P1 through which the splined, or inferior portion 54 of thefirst rod 12 is able to be slidably received. The sleeve insert 82 alsohas a groove 110 extending parallel to the center line of the sleeveinsert into the convex articulation surface 88. The groove 110 isadapted to receive the protrusion 98 for limiting roll of the sleeveinsert 82 within the body 80. The pivot point P1 is defined in thepassage 100, where upon assembly the first rod 12 passes through thefirst pivot point P1 such that the longitudinal axis of the rod at thefirst pivot point P1 is generally concentric with the center of thepassage 100.

As shown, the passage 100 has a non-circular cross-section (e.g., asplined cross-section corresponding to the inferior portion 54 of thefirst rod 12). Upon mating the non-circular cross-sections of the firstrod 12 and the passage 100, rotation of the first rod 12 relative to thesleeve insert 82 is substantially inhibited or prevented. In someembodiments, the passage 100 defines a plurality (e.g., six) of inwardsplines 112 and a plurality of recessed pockets 114 (e.g., six) betweenthe splines 112. The splines 112 are optionally trapezoidal (e.g., likethe teeth of a gear) in shape overall. A variety of shapes arecontemplated for the splines 112, including involute shapes, forexample. The pockets 114 optionally include corner recesses 116 that arerounded in shape (e.g., to help prevent binding between the passage 100and the first rod 112 during sliding of the first rod 112 in the passage100). In some embodiments, the splines 60, 112 are designed to helpmaximize efficiency of torque transfer between the first rod 12 and thesleeve insert 82 while reducing contact pressure angle(s) between thecomponents.

The protrusion 98 is optionally a pin with a head 120, a neck 122, and abody 124, the neck 122 being located between the head 120 and the body124. The head 120, the neck 122, and the body 124 are optionallysubstantially cylindrical with the head 120 having a greater diameterthan the body 124 and the body 124 having a greater diameter than theneck 122. The protrusion 98 is received in the pin chase 90 with thehead 120 received in the seat 92 such that the head projects into theaperture 84. In some embodiments the protrusion 98 is press fit into thepin chase 90 and/or welded, adhered, or otherwise secured within the pinchase 90. In other embodiments the protrusion is temporary and isremovable, providing temporary prevention of roll of the sleeve insert82 within the body 80 so that the first stabilizing anchor 16 is able tobe adjusted so that the rod 12 is free to rotate.

FIGS. 6, 7, and 8 show the sleeve insert 82 being assembled into thebody 80 by positioning the sleeve insert 82 perpendicular, or edgewise,relative to the aperture 84 (FIG. 5) and sliding the sleeve insert 82into the channels 94, 96. In other embodiments, the sleeve insert 82 isable to be inserted at another angle (45 degrees, for example). In thisposition, the diametric plane of the sleeve insert 82 is generallyparallel to the centerline Z of the aperture 84. In alternate terms, thecenterline W of the sleeve insert 82 is generally parallel to thediametric plane of the aperture 84. Once received in the aperture 84 viathe channels 94, 96, the sleeve insert 82 is rotated such that theprotrusion 98 (FIG. 3) is received in the groove 110 (e.g., as shown inFIGS. 3, 4, and 5). With the protrusion 98 slidably received in thegroove 110, the pitch and yaw of the first rod 12 are still able tochange while roll is substantially limited. The first rod 12 alsoremains free to slide axially within the sleeve insert 82, according tosome embodiments.

As relative rotation between the sleeve insert 82 and the body 80 isalso substantially inhibited, relative rotation between the first rod 12and the first stabilizing anchor 16 is substantially inhibited orlimited, allowing the first rod 12 to be maintained at a pre-selectedrotational position relative to the first stabilizing anchor 16. It alsoshould be understood that other cross-sectional shapes for each of thepassage 100 (FIG. 3) and first rod 12 can be selected to allow somedegree of rotation about the longitudinal axis X within a predefinedrange.

In some embodiments, the second stabilizing anchor 18 is substantiallysimilar to the first stabilizing anchor 16, including any desiredcombination of previously-described features. As shown in FIG. 9, thesecond stabilizing anchor 18 is substantially similar to the firststabilizing anchor 16, with the exception that the second stabilizinganchor 18 has a smooth bore 130 for receiving the first rod 12. Thesecond stabilizing anchor 18 is adapted to be fixed, and provides meansfor fixation to a second vertebra, such as a second vertebra 42B (FIG.1). The second stabilizing anchor 18 is further adapted to receive, andprovides means for receiving the first rod 12 (FIG. 1) such that thesecond stabilizing anchor 18 limits translational movement of the firstrod 12 except along the longitudinal axis X (i.e., the secondstabilizing anchor 18 allows sliding movement of the first rod 12) andallows the first rod 12 to change in at least pitch and yaw about asecond pivot point P2. Moreover, as shown the second stabilizing anchor18 allows the first rod 12 to change in roll about the second pivotpoint P2.

The first anchor 20 is shown in greater detail in FIG. 10, according tosome embodiments. The first, second, third, and fourth anchors 20, 22,24, 26 (FIG. 1) are optionally substantially similar, and thus variousfeatures of the anchors are described in association with the firstanchor 20, where when referenced, features of the first anchor 20 aredesignated with reference numbers and similar features of the second,third, and fourth anchors 22, 24, 26 are designated with the samereference numbers followed by a “B,” “C,” and “D,” respectively.

As shown, the first anchor 20 includes a mounting portion 140, a headportion 142, and a connection portion 144. The mounting portion 140 hasa top surface 150, a bottom surface 152, and a slot 154 for receivingone of the fasteners 36, such as a pedicle screw or other bone screw.The slot 154, also described as an aperture, is elongate and extendslongitudinally in a first direction R1.

The head portion 142 is substantially U-shaped, including a first prong160 and a second prong 162 defining a pocket 164 for receiving one ofthe first and second rods 12, 14. As shown, the prongs 160, 162 arethreaded for receiving a clamping screw 166 adapted to engage and secureone of the first and second rods 12, 14 immobilized within the pocket164.

The connection portion 144 extends in a second direction R2 that isoffset from the first direct R1. The connection portion 144 extendsbetween the mounting portion 140 and the head portion 142 at an angle ofabout 45 degrees, for example, relative to the first direction R1.

The first and second transverse anchors 28, 30 are optionallysubstantially similar, and thus various features of both the first andsecond transverse anchors are described in association with the firsttransverse anchor 28, where when referenced, features of the firsttransverse anchor 28 are designated with reference numbers and similarfeatures of the second transverse anchor 30 are designated with the samereference numbers followed by a “B.”

The first transverse anchor 28 is shown in greater detail in FIG. 11,according to some embodiments. As shown, the first transverse anchor 28includes a mounting portion 170, a head portion 172, a connectionportion 174, and an arm portion 176. The mounting portion 170 has a topsurface 180, a bottom surface 182, and a slot 184 for receiving one ofthe fasteners 36, such as a pedicle screw. The slot 184 is elongate andextends longitudinally in a first direction R1. In some embodiments, thearm portion 176 generally extends away from the mounting portion 170 forpurpose of coupling to the first rod 12 and the head portion serves tocouple the first transverse anchor 28 to the second rod 14.

The head portion 172 is substantially U-shaped, including a first prong190 and a second prong 192 defining a pocket 194 for receiving thesecond rod 14. As shown, the prongs 190, 192 are threaded for receivinga clamping screw 196 adapted to engage and secure the second rod 14immobilized within the pocket 194.

The connection portion 174 extends in a second direction R2 that isoffset from the first direct R1. The connection portion 174 extendsbetween the mounting portion 170 and the head portion 172 at an angle ofabout 45 degrees, for example, relative to the first direction R1. Inother embodiments, the connection portion 174 extends between themounting portion and head portion 170, 172 at another angle, such asfrom about 30 to about 60 degrees, or at no angle (i.e., the portions170, 172, 174 are generally in-line with one another).

The arm portion 176 includes a neck section 200 that is substantiallyelongate and cylindrical, a shoulder section 202 that is flared anddefines an abutment face 203, and a terminal section 204 that isthreaded. The arm portion 176 extends longitudinally in the firstdirection R1. The arm portion 176 is adapted to extend across a portionof one of the vertebrae 42 for example, from one side of the spinalcolumn 40 to an opposite side of the spinal column 40. For example, thefirst transverse anchor 28 is secured to one of the vertebrae 42 suchthat the arm portion 176 extends laterally across the vertebra 42.

FIG. 12 shows the first adjustment assembly 32 from an isometric view,FIG. 13 shows the adjustment 32 assembly from a cross-sectional view,FIG. 14 shows the adjustment assembly 32 from a plan view with a portionof the housing removed, and FIG. 15 shows the adjustment assembly 32from a plan view with the housing intact, according to some embodiments.

The first adjustment assembly 32 is adapted to adjust, and providesmeans for adjusting tension and/or a distance between the first rod 12and the first transverse anchor 28. The first and second adjustmentassemblies 32, 34 are optionally substantially similar. Thus, variousfeatures of both the first and second adjustment assemblies 32, 34 aredescribed in association with the first adjustment assembly 32, wherefeatures of the first adjustment assembly 32 are designated withreference numbers and similar features of the second adjustment assembly34 are designated with the same reference numbers followed by a “B.”

As shown, the first adjustment assembly 32 includes a tensioner 208, thetensioner 208 including a housing 210, a reel 212, a circumferentialgear 214 surrounding the reel 212, a drive gear 216 in contact with thecircumferential gear 214, and an actuation head 218. The firstadjustment assembly 32 also includes an elongate connector 219 adaptedto be wound about the reel 212.

The reel 212, as well as the circumferential gear 214 and drive gear 216are maintained at least partially within the housing 210. In turn, thehousing 210 is adapted to be secured to the first rod 12. For example,the housing 210 optionally forms a central lumen 220 through which therod first 12 is receivable. Upon inserting the first rod 12 through thecentral lumen 220, the housing 210 is adapted to be clamped onto thefirst rod 12.

In some embodiments, the housing 210 defines a first side 223 and asecond side 224 and incorporates a clamshell design (e.g., a firstportion adjustably secured to a second portion) adapted to be tightenedonto the first rod 12 (e.g., using one or more fasteners). Thus, in someembodiments, the first adjustment assembly 32 is substantially fixedwith respect to the first rod 12. Other designs, such as monolithichousing designs and others are contemplated. Moreover, in someembodiments, the first adjustment assembly 32 is movable with respect tothe first rod 12, for example being able to slide and/or rotate aboutthe first rod 12.

The central lumen 220 of the housing 210 defines a longitudinal axis Land forms a pocket 226 for receiving the reel 212 and thecircumferential gear 214 such that the reel 212 and the circumferentialgear 214 are able to rotate within the housing 210. The housing 210 alsodefines a pair of opposed apertures 228 for receiving ends of the drivegear 216 to retain the drive gear 216 while allowing the drive gear 216to rotate. As shown, the housing 210 also defines a top 230 and a bottom232, where the bottom 232 forms a lower opening 234 and a raisedabutment 236 adjacent to the lower opening 234, toward the first side223 of the housing 210.

As shown, the reel 212 includes a helical groove 238 for receiving theelongate connector 219 and a raised anchor block 240 for securing theelongate connector 219 to the reel 212. For example, the anchor block240 optionally includes an aperture for receiving the elongate connector219 and is welded or otherwise fastened in the aperture. The reel 212,as well as the circumferential gear 214, form a lumen 242 for coaxiallyreceiving the first rod 12. In some embodiments, by receiving the firstrod 12 through the reel 212 and circumferential gear 214, an overallsize, or profile, of the tensioner 208 is able to be reduced.

As shown, the circumferential gear 214 is connected to, and coaxiallyaligned with the reel 212. The circumferential gear 214 is engaged withthe drive gear 216 such that rotation of the drive gear 216 causes thecircumferential gear 214, and thus, the reel 212, to turn (e.g., in aworm or crossed-spur gear configuration).

The elongate connector 219 includes a flexible tether 250 and aconnector head 252. In some embodiments, the flexible tether 250 issubstantially flexible and able to be pivoted in a multiple directionsand/or be spooled or wound, for example. Suitable flexible materialsinclude wire and stranded cables, monofilament polymer materials,multifilament polymer materials, multifilament carbon or ceramic fibers,and others. In some embodiments, the flexible tether 250 is formed ofcobalt chromium alloy or titanium alloy wire or cable, although avariety of materials are contemplated. The flexible tether 250 includesa terminal cap 256 (FIG. 16) adapted to be secured in the connector head252. The terminal cap 256 has a rounded (e.g., semi-circular) head andis optionally swaged onto the flexible tether 250. In other embodiments,rather than a swage a loop or other feature is implemented to connect ofthe connector head 252.

FIG. 16 is a cross-sectional view of the connector head 252, accordingto some embodiments. As shown, the connector head 252 defines aninternal bore 260 and forms a collar 262, a raised shoulder 264, and aneck 266. The internal bore 260 has a rounded seat 270 (e.g., asubstantially concave seat). The connector head 252 also has a first end272 and a second end 274, the second end 274 having a rounded innerprofile 276 (like the horn of a trumpet). The flexible tether 250 issecured to the connector head 252 by receiving the terminal cap 256 inthe rounded seat 270 in a complementary fit.

The elongate connector 219, also described as a connector or cable, isadapted to be secured to the first transverse anchor 28 and the firstadjustment assembly 32. So secured, the elongate connector 219 definesan effective length between the first transverse anchor 28 and tensioner208 and, and thus the first rod 12 (although, in some embodiments, theelongate connector 219 is secured directly to the rod 12). As described,in some embodiments, the tensioner 208 is adapted to modify, andprovides means for modifying, the effective length of the tether 250 ofthe elongate connector 219 (e.g., by spooling the tether 250 on and offof the reel 212).

The elongate connector 219 is attached or secured to the reel 212 andpasses out of the housing 210 through the lower opening 234 in thehousing 210. Although a lower opening is shown, in other embodiments theopening is in the side or top, for example. Actuation of the drive gear216 via the actuation head 218 turns the circumferential gear 214, whichturns the reel 212, thus winding (or unwinding, depending on thedirection in which the reel 212 is turned) the elongate connector 219about the reel 212. Rotation of the reel 212 in the appropriatedirection draws the tether 250 in toward the tensioner 208 (FIG. 17),pulling the first transverse anchor 28 toward the tensioner 208,according to some methods of correcting a spinal defect.

FIG. 17 shows the first actuation assembly 32 as it would appear in afirst, extended state attached to the uncorrected spinal column 40(e.g., FIG. 18) and as it would appear in a second, retracted state asattached to the corrected spinal column (e.g., FIG. 19), according tosome embodiments. As shown, the connector head 252 engages the raisedabutment 236 and the housing 210 as the tether 250 is drawn into thehousing 210. This engagement and/or the orientation of the lower opening234 (i.e., with the tether 250 exiting the housing 210 through thebottom) helps generate a moment M on the first transverse anchor 28 (notshown in FIG. 17) thereby helping to derotate the third vertebra 42C towhich the first transverse anchor 28 is attached. The ability of thetether 250 to flex and bend at the second end 274 of the connector head252 helps generate a polyaxial connection at the second end 274 andfacilitates generation of the moment M as described.

FIG. 18 shows the assembled system 10. In some embodiments, assembly ofthe system 10 and associated methods of correcting the spine 40 includesecuring the stabilizing anchors 16, 18 to inferior and superiorportions of the spine 40. For example, the first stabilizing anchor 16is optionally secured to the spine 40 by driving one of the plurality offasteners 36 through each of the through holes 74 and into one or moreof the vertebrae 42. For example, as shown in FIG. 1, the firststabilizing anchor 16 is secured with one of the fasteners 36 driveninto a pedicle of the first vertebra 42A and another of the fasteners 26driven into a pedicle of another vertebra that is adjacent to the firstvertebra 42A. The second stabilizing anchor 18 is similarly secured tothe second vertebra 42B and a vertebra adjacent the second vertebra 42B.As shown, each of the first and second stabilizing anchors is secured onthe first side 40A of the spine.

The first and second actuation assemblies 32, 34 are slid onto orotherwise coupled to the first rod 12 and then secured (e.g., clamped)at a desired location along the rod 12. The first rod 12 is received inthe first and second stabilizing anchors 16, 18, with the splined, orinferior portion 54 of the first rod 12 slidably received in the sleeveinsert 82 of the first stabilizing anchor 16 and the superior portion 50of the rod 12 slidably received in the second stabilizing anchor 18.Thus, in some embodiments the first rod 12 extends along the first side40A of the spine 40 and is secured against lateral movement relative toa portion of the spine 40.

In some embodiments, the first rod 12 is attached by the stabilizinganchors 16, 18 to pedicles and/or transverse processes on the first side40A of the spinal column 40 and is able to slide axially relative to thefirst and/or second stabilizing anchors 16, 18. In other embodiments,the rod 12 is attached by the stabilizing anchors 16, 18 to the secondside 40B of the spinal column 40, on different sides of the spinalcolumn 40 (e.g., the first stabilizing anchor 16 on the left side andthe second stabilizing anchor 18 on the right side), or along themid-line of the spinal column 40. In other embodiments, the first rod 12is adjustable length to compensate for changes in length of the spinalcolumn 40.

By limiting rotation, or roll, of the first rod 12 relative to the firststabilizing anchor 16, the bend in the first rod 12 is oriented andmaintained in a desired rotational position. Maintaining the rotationalorientation at one end (i.e., at the first stabilizing anchor 16) isuseful, for example, to help ensure that the bend or shape of the rod 12consistently follows or otherwise appropriately tracks a desiredcurvature of a spinal column 40. Freedom of rotation at the other end ofthe first rod 12 (i.e., at the second stabilizing anchor 18), however,still permits the spinal column 40 to have more natural movement whilethe corrective forces are being applied.

Though not shown, the system 10 optionally includes one or more stopfeatures for limiting axial sliding, or translation of the first rod 12relative to one of the stabilizing anchors to a desired range.Generally, sliding of the first rod 12 in a particular axial directionis substantially limited, or arrested, when a stop feature engages, orabuts an adjacent stabilizing anchor 16, though other stop mechanismsare contemplated.

The first and second transverse anchors 28, 30 are secured to one ormore of the vertebrae 42, such as a third vertebra 42C in an apicalregion A of the spine 40 and a fourth vertebra 42D in an apical region Aof the spine 40. The first transverse anchor 28 is secured to the thirdvertebra 42C by driving one of the fasteners 36 through the slot 184 inthe mounting portion 170 of the first transverse anchor 28. For example,the first transverse anchor 28 is optionally secured into a pedicleand/or transverse processes of the third vertebra 42C on the second side40B of the spine 40. The second transverse anchor 30 is optionallysimilarly secured on the second side of the spine 42B to a pedicle ofthe fourth vertebra 42D. As shown, the arm portions 176, 176B (FIG. 11)of the first and second transverse anchors 28, 30 extend from the secondside 40B of the spine 40 to the first side 40A of the spine 40.

The first and second actuation assemblies 32, 34 are secured to thefirst and second transverse anchors 28, 30 by attaching (e.g., screwing)the connector heads 252, 252B of the elongate connectors 219, 219B tothe threaded terminal sections of the transverse anchors 28, 30. Somemethods include adjusting a curvature of the spine 40 to a desiredcurvature using the actuation assemblies 32, 34. For example, thetensioners 208, 208B of the first and second actuation assemblies 32, 34are actuated (independently or simultaneously) in order to draw theelongate connectors 219, 219B into the respective tensioners 208, 208B,thereby drawing the third and fourth vertebrae 42C, 42D and surroundingportions of the spine 40 toward the first rod 12 and to a more desirablespinal curvature.

As shown in FIG. 19, the first and third anchors 20, 24 are secured to afifth vertebra 42E and the second and fourth anchors 22, 26 are securedto a sixth vertebrae 42E, 42F of the spine 40, thought each of theconnectors is optionally secured to a different vertebra. The firstanchor 20 is secured along the spine 40 at a location between the firststabilizing anchor 16 and the first actuation assembly 32 and the secondstabilizing anchor 18 is secured at a location between the secondstabilizing anchor 18 and the second actuation assembly 34. The firstand second anchors 20, 22 are secured on the first side 40A of the spine40 whereas the third and fourth anchors 24, 26 are secured on the secondside 40B of the spine 40 opposite the first and second anchors 20, 22,for example. The first anchor 20 is secured to a pedicle of the fifthvertebra 42E by driving one of the fasteners 36 into the pedicle throughthe slot 154 in the mounting portion 140 of the first anchor 20 (FIG.The second, third, and fourth anchors 22, 24, 26 are optionallysimilarly secured to the spine 40.

If desired, the first rod 12 is received in the first and second anchors20, 22 (e.g., prior to securing the first and second anchors 20, 22 tothe spine 40) and the first rod 12 is secured in the pocket 164 of thefirst anchor 20 using the clamping screw 166 (FIG. 10). The first rod 12is similarly secured in the second anchor 22, thereby immobilizing thefirst rod 12 between the first and second anchors 20, 22.

As shown in FIG. 20, the second rod 14 is received in the transverseanchors 28, 30, and optionally in the third and fourth anchors 24, 26(e.g., prior to securing the third and fourth anchors 24, 26 to thespine 40) in order to provide secondary stabilization to thecorresponding region of the spine 40. For example, the second rod 12 issecured in the pocket of the third anchor 24 using the clamping screwand in the pocket 194 of the first transverse anchor 28 using theclamping screw 196 (FIG. 11). The second rod 14 is similarly secured inthe second transverse anchor 30 and the fourth anchor 26, therebyimmobilizing the second rod 14 between the third and fourth anchors 24,26. As shown, the first and second rods 12, 14 are on opposite sides ofthe spine 40, immobilizing a desired region of the spine 40 (e.g., aspart of a spinal fusion process), such as an apical region A of thespine 40. As appropriate, bone cement, fillers, or other materials areoptionally employed with one or more vertebrae 42 to facilitateintervertebral fusion. In other embodiments, the system 10 is configuredto avoid fusion of the spine 40. For example, the first and/or secondrods 12, 14 are optionally substantially flexible such that the system10 allows sufficient movement of the spine 40 to help avoidintervertebral fusion while still providing structural support duringgrowth and remodeling of the spine 40.

As shown in FIG. 21, if desired (e.g., once the spine 40 is stabilized),the first rod 12 is clipped, cut, broken, or otherwise portioned betweenthe first anchor 20 and the first stabilizing anchor 16 and between thesecond anchor 22 and the second stabilizing anchor 18. As shown in FIG.22, the superior and inferior portions of the first rod 12 areoptionally removed from the first and second stabilizing anchors 16, 18and the first and second stabilizing anchors 16, 18 are removed from thespine 40. As another alternative, the first rod 12 is not portioned andis left free to move in the stabilizing anchors 16, 18, for example.Moreover, if desired, the entire system 10 is optionally removed after adesired amount of fusion of the spine has been achieved and/or aftersufficient growth and remodeling of the spinal curvature has beenachieved. For example, once a diseased area of the spine hassufficiently healed (e.g., after being fused and stabilized) thestability provided by the system 10 may no longer be required.

Thus, according to various embodiments, the spinal column 40 (and thus,the person) is able to twist, bend side-to-side, and bendforward-and-backward in a more natural manner while corrective forcesare being applied to the spinal column 40 and/or to achieve a desiredcorrection of the spine 40. In some embodiments, the effective lengthsof the actuation assemblies 34, 36, and specifically the elongateconnectors 219, 219B are adjusted (e.g., periodically or all at onetime), bringing the spinal column into natural alignment, while thesystem 10 facilitates a more natural movement of the spinal column 40(e.g., twisting and bending forward-and-backward and side-to-side) dueto the freedom of movement afforded by the system 10. During a secondaryfusion procedure, the second rod 14 is secured to the corrected spine 40opposite first rod 12 to rigidly secure a region of the spine for fusionas shown in FIG. 23. If desired, this includes immobilizing an apicalregion A of the spine 40 and leaving a superior region of the spine 40adjacent to the apical region A and an inferior region of the spine 40adjacent to the apical region A free to move in at least one degree offreedom. The at least one degree of freedom optionally includeselongation, or growth, compression, twisting, and/or flexing. In someembodiments, the freedom of movement of the first rod 12 provided by thestabilizing anchors 16, 18 helps facilitate this motion. In otherembodiments, removal of one or more portions of the system 10 (e.g.,clipping and removing portions of the rod 12) facilitates this motion.

In some embodiments, by linking the convex and concave sides of thespine 40 together, stress on the spine 40 is distributed at theanchor-vertebral interfaces as well as stiffening the apical region A ofthe spine, helping to stabilize the deformity. Thus, in addition to theconnection between the apical region A and the first rod 12, the lateralconnection between the rods 12, 14 optionally helps resist vertebralrotation and lateral translation).

As previously indicated, in some embodiments, the spine 40 is optionallycorrected, or tensioned toward the first rod 12 prior to securing thesecond rod 14 to the spine 40. In other embodiments, the correctivemethod includes securing the second rod 14 to the spine 40 (e.g., topartially or fully correct spinal curvature the apical region A) andthen tensioning the second rod 14 toward the first rod 12 in order tocorrect the spine 40 or portions thereof (e.g., a curvature of the spine40 superior and/or inferior to the apical region A).

As previously indicated, the system 10 may include greater or fewercomponents according to various embodiments. FIG. 24 is an example ofthe system 10, which includes correction and secondary stabilizationfeatures, the system 10 including fewer components. With reference toFIG. 18, the system 10 is optionally used to correct a spinal deformity(including a total or partial correction) and then the second rod 14 isreceived in, and secured in, the pockets 194, 194B of the first andsecond transverse anchors 28, 30. The secondary stabilization providedby the second rod 14 is optionally used to facilitate fusion of thespine 40, including use of growth promoters or other materials forencouraging intervertebral fusion.

FIG. 25 shows another stabilizing anchor 16A (also described as a rodanchor) of the system 10, according to some embodiments. The firststabilizing anchor 16A is adapted, or otherwise structured, to bemounted, or fixed to one or more of the vertebrae 42, such as a firstvertebra 42A (FIG. 1) located at an inferior position, or otherposition, along the spine 40.

As shown, the first stabilizing anchor 16A is substantially similar tothe first stabilizing anchor 16. The first stabilizing anchor 16Aincludes a mounting portion 70A and a housing portion 72A. The mountingportion 70A optionally includes through holes 74A for receiving one ofthe fasteners 36, such as a pedicle screw or similar device to securethe mounting portion 70A to one or more vertebrae 42, such as the firstvertebra 42A.

The housing portion 72A of the first stabilizing anchor 16A includes abody 80A and a sleeve insert 82A. The body 80A is substantially similarto the body 80 of the first stabilizing anchor 16 with an optionaldifference being that the body 80A is split by a gap 298A dividing thebody 80A into a lower portion 300A and an upper portion 302A that can beclamped together with adjustment member 304A (e.g., a bolt) securedacross the gap 298A. The sleeve insert 82A, in turn, is substantiallysimilar to the sleeve insert 82 with the addition of a gap 306A thatfacilitates clamping of the sleeve insert 82A onto the rod 12. Forexample, upon sufficiently tightening the adjustment member 304A, thesleeve insert 82A is clamped onto rod 12 to arrest sliding and rollingmotion of the rod 12 through the sleeve insert 82A. Additionally, theclamping action of the body 80A on the sleeve 82A arrests changes inpitch and yaw. In different terms, the rod 12 is able to be selectivelylocked relative to the stabilizing anchor 16A.

FIG. 26 shows another stabilizing anchor 16B (also described as a rodanchor) of the system 10, according to some embodiments. The firststabilizing anchor 16B is adapted, or otherwise structured, to bemounted, or fixed to one or more of the vertebrae 42, such as a firstvertebra 42A (FIG. 1) located at an inferior position, or otherposition, along the spine 40.

As shown, the first stabilizing anchor 16B is substantially similar tothe first stabilizing anchors 16, 16A and includes a clamping mechanismsimilar to first stabilizing anchor 16A. The first stabilizing anchor16B includes a mounting portion 70B and a housing portion 72B. Themounting portion 70B differs from the mounting portion 70A of the firststabilizing anchor 16A in that the mounting 70B portion includes asingle through hole 74A for receiving one of the fasteners 36, such as apedicle screw or similar device to secure the mounting portion 70B toone or more vertebrae 42, such as the first vertebra 42A. In someembodiments, the first stabilizing anchor 16B is adapted to be securedto a single vertebra, as compared to being secured across multiplevertebrae.

FIG. 27 shows the system 10 employing the first stabilizing anchor 16Aand a second stabilizing anchor 18A that is substantially the same asthe first stabilizing anchor 16A, according to some embodiments. Asshown in FIG. 27, the rod 12 of the system 10 is able to slide andchange in pitch, yaw, and roll at both of the anchors 16A, 18A and isalso able to be selectively locked against sliding, pitch, yaw, and rollat each of the first and second stabilizing anchors 16A, 18A. Selectivelocking at one or both anchors 16A, 18A is optionally employed for avariety of reasons, including for performing partial or total fusion, tofacilitate a correction, or adjustment process using the tensioners 32,34, or to facilitate assembly of the system 10 prior to a correctionoperation.

FIG. 28 shows the system 10 employing the first and second stabilizinganchors 16A, 18A similarly to FIG. 27, according to some embodiments. Inaddition, the first anchor 20 and the second anchor 22 shown in FIG. 27are replaced by first and second anchors 20B, 22B, which are eachsubstantially the same as the first stabilizing anchor 16B (FIG. 26). Asshown in FIG. 28, the rod 12 of the system 10 is able to slide andchange pitch, yaw and roll at the anchors 16A, 18A, 20B, 22B and is alsoable to be selectively locked against sliding, pitch, yaw, and roll ateach of the anchors 16A, 18A, 20B, 22B as desired. Once again, selectivelocking at any of the anchors 16A, 18A, 20B, 22B is optionally employedfor a variety of reasons, including for performing partial or totalfusion, to facilitate a correction, or adjustment process using thetensioners 32, 34, or to facilitate assembly of the system 10 prior to acorrection operation.

FIG. 29 shows the system 10 employing a plurality of anchors, each ofwhich is substantially similar to the first stabilizing anchor 16B (FIG.26). As shown in FIG. 29, the rod 12 of the system 10 is able to slideand change in pitch, yaw and roll at the anchors 16B, 18B, 20B, 22B. Thefirst anchor 16B optionally employs a chase feature similar to thosepreviously described to limit roll. Alternatively, the first anchor 16Bfreely permits roll of the rod 12. As shown in FIG. 29, the rod 12 has ahigh degree of freedom, while being laterally constrained, as desired.In particular, the rod 12 is also able to be selectively locked againstsliding, pitch, yaw, and roll at each of the anchors 16B, 18B, 20B, 22Bas desired. Once again, selective locking at any of the anchors isoptionally employed for a variety of reasons, including for performingpartial or total fusion, to facilitate a correction, or adjustmentprocess using the tensioners 32, 34, or to facilitate assembly of thesystem 10 prior to a correction operation. From the foregoing, it shouldbe understood that a variety of numbers and configurations of theanchors is contemplated. Though not specifically shown, it should alsobe understood that any of the foregoing anchors are employed with thesecond rod 14 on the second side of the spine.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

We claim:
 1. A system for correcting a spinal deformity, the system comprising: a first rod adapted to extend along a first side of a spine of a patient; a first anchor adapted to be fixed to a vertebra of the spine and to receive the first rod such that the first rod is secured against substantial lateral translation relative to the first anchor and the first rod is allowed to slide axially relative to the first anchor through a first pivot point and to change in at least two of pitch, yaw, and roll about the first pivot point during correction; a second anchor adapted to be fixed to a vertebra of the spine and to receive the first rod such that the first rod is secured against substantial lateral translation relative to the second anchor and is allowed to change in at least pitch and yaw about a second pivot point during correction; a second rod adapted to extend along a second side of the spine of the patient; a third anchor adapted to be fixed to a vertebra of the spine and to receive the second rod such that the second rod is secured against substantial lateral translation relative to the third anchor during correction and such that the second rod is secured against changes in pitch, yaw, roll, and axial sliding; a fourth anchor adapted to be fixed to a vertebra of the spine and to receive the second rod such that the second rod is secured against substantial lateral translation relative to the fourth anchor; and a lateral coupling adapted to extend between and laterally secure the first rod and the second rod such that the lateral coupling facilitates derotation and translation of the spine.
 2. The system of claim 1, wherein the lateral coupling comprises: an arm adapted to extend from the second side of the spine toward the first side of the spine and to receive the second rod, a first flexible connector secured to the arm, and an adjuster adapted to be secured to the first rod and to shorten an effective length of the first flexible connector to tension the arm toward the first rod.
 3. The system of claim 2, wherein the arm is formed as a part of the third anchor.
 4. The system of claim 2, wherein the third anchor includes a head defining a receptacle for receiving the second rod, a fixation member adapted to secure the head of the third anchor to the second side of the spine, and an arm extending from the head and adapted to extend from the second side of the spine to the first side of the spine.
 5. The system of claim 4, wherein the third anchor includes a U-shaped receptacle for receiving the second rod.
 6. The system of claim 4, wherein the fixation member includes a pedicle screw.
 7. The system of claim 1, wherein the second rod is substantially shorter than the first rod.
 8. The system of claim 1, wherein the second rod has a length corresponding to an apical region of a spine of a patient.
 9. The system of claim 1, further comprising an anchor adapted to secure the first rod at a desired position and to secure the first rod against changes in pitch, yaw, roll, and axial sliding.
 10. The system of claim 1, wherein the lateral coupling comprises: an arm adapted to extend from the second side of the spine toward the first side of the spine and to receive the second rod, a first connector secured to the arm, and an adjuster adapted to tension the arm toward the first rod.
 11. The system of claim 1, wherein the third anchor is adapted to secure the second rod at a desired position and to selectively secure the second rod against changes in pitch, yaw, roll, and axial sliding.
 12. A system for correcting a spinal deformity, the system comprising: a first rod adapted to extend along a first side of a spine of a patient; a first anchor adapted to be fixed to a vertebra of the spine and to receive the first rod such that the first rod is secured against substantial lateral translation relative to the first anchor and the first rod is allowed to slide axially relative to the first anchor through a first pivot point and to change in at least two of pitch, yaw, and roll about the first pivot point during correction; a second anchor adapted to be fixed to a vertebra of the spine and to receive the first rod such that the first rod is secured against substantial lateral translation relative to the second anchor and is allowed to change in at least pitch and yaw about a second pivot point during correction; a second rod adapted to extend along a second side of the spine of the patient; a third anchor adapted to be fixed to a vertebra of the spine and to receive the second rod such that the second rod is secured against substantial lateral translation relative to the third anchor; a fourth anchor adapted to be fixed to a vertebra of the spine and to receive the second rod such that the second rod is secured against substantial lateral translation relative to the fourth anchor; and a lateral coupling adapted to extend laterally between the first rod and the second rod such that the lateral coupling facilitates derotation and translation of the spine, the lateral coupling comprising: an arm adapted to extend from the second side of the spine toward the first side of the spine and to receive the second rod; an adjuster adapted to be secured to the first rod; and a first connector adapted to be secured between the arm and the adjuster such that the adjuster is actuable to tension the arm toward the first rod.
 13. The system of claim 12 configured such that actuation of the adjuster causes a first portion of the lateral coupling to engage with a second portion of the lateral coupling to generate a moment between the arm and the adjuster.
 14. The system of claim 12 configured such that actuation of the adjuster causes a first portion of the lateral coupling to engage with a second portion of the lateral coupling to derotate and translate the spine.
 15. The system of claim 12 configured such that actuation of the adjuster causes a first portion of the lateral coupling to engage with a second portion of the lateral coupling to adjust the distance between the first rod and the third anchor. 